This invention relates to an apparatus for processing rubber and more particularly to an extruder with an extrusion screw which plasticates and mixes rubber compounds.
The conventional practices for processing rubber and its associated compounds is to combine them in a milling or calendering machine which comprises two rotating rollers which have a small gap therebetween. As these rollers rotate, the rubber compound undergoes a shearing action involving a plastication and mastication. The working action of the rollers is substantially at the nip of the rollers, with the remaining portion of the cycle undergoing a relaxation and a reorientation of the distorted particles. It is only when the rubber compound goes through the nip or gap of the rollers that the material is worked. The present invention provides a continuous and repeated shearing action with the use of an extruder and extruder screw, wherein the extruder screw design permits repeated mastication and shearing along its length. Such apparatus improves the efficiency of the extruder in this process. The apparatus is novel over conventional extruders which could not work the rubber to its proper temperature and plasticity.